1. Field of the Invention
The present invention relates generally to vacuum arc remelting, and more particularly to a spectroscopy-based safety system for a vacuum arc remelt furnace.
2. Description of the Related Art
Vacuum arc remelting (VAR) is a process utilized throughout the specialty metals industry to produce high-quality ingots, such as, for example, specialty steel ingots, nickel-based superalloy ingots and titanium alloy ingots. In vacuum arc remelting, a consumable alloy electrode, typically having a cylindrical shape, is lowered into a VAR furnace that includes a water-cooled copper crucible. A starting material, such as a collection of metal chips, is provided at the bottom of the crucible. The VAR furnace is evacuated and a dc arc is struck between the electrode and the starting material. The heat from the arc continuously melts the tip of the electrode as it is translated downwardly within the crucible, causing molten metal to drip off of the tip of the electrode and into the bottom of the crucible where it solidifies. As the droplets of molten metal fall, high vapor pressure elements and entrapped gasses are removed as a result of the vacuum condition inside the furnace. The objective of VAR is to produce ingots that are free of microstructure and chemical composition defects that are often associated with uncontrolled solidification during casting.
Sometimes during operation of a VAR furnace, the electrode arcs to the water-cooled copper casting crucible. This type of arcing is dangerous because, under certain conditions, it can lead to a steam/hydrogen explosion inside the VAR furnace. For safety reasons, the existence and level of such arcing must be constantly monitored. Currently, electrode to crucible arcing is manually monitored by an operator by visually observing the VAR furnace. As will be appreciated, such manual monitoring is susceptible to human error. Thus, there is a need for an automated system and method for monitoring for electrode to crucible arcing in a VAR furnace.